The invention relates to methods of producing ternary particles, especially crystalline nanoparticles, by laser pyrolysis. In particular, the invention relates to the production of crystalline lithium manganese oxide directly by laser pyrolysis.
Advances in a variety of fields have created a demand for many types of new materials. In particular, a variety of chemical powders can be used in many different processing contexts, such as the production of batteries. The microminiaturization of electronic components has created widespread growth in the use of portable electronic devices such as cellular phones, pagers, video cameras, facsimile machines, portable stereophonic equipment, personal organizers and personal computers. The growing use of portable electronic equipment has created ever increasing demand for improved power sources for these devices. Relevant batteries include primary batteries, i.e., batteries designed for use through a single charging cycle, and secondary batteries, i.e., batteries designed to be rechargeable. Some batteries designed essentially as primary batteries may be rechargeable to some extent.
Batteries based on lithium have been the subject of considerable development effort and are being sold commercially. Lithium based batteries generally use electrolytes containing lithium ions. The negative electrodes for these batteries can include lithium metal or alloy (lithium batteries), or compositions that intercalate lithium (lithium ion batteries). Preferred electroactive materials for incorporation into the positive electrodes are compositions that intercalate lithium. The compositions that intercalate lithium, for use in the positive electrodes, generally are chalcogenides such as metal oxides that can incorporate the lithium ions into their lattice.
Manganese oxides and lithium manganese oxides with various stoichiometries have been noted as promising materials for use in positive electrodes for lithium based batteries. In particular, appropriate manganese oxides can intercalate lithium ions into their crystal structure to form lithium manganese oxides. Lithium manganese oxides are useful for the production of lithium based secondary batteries. Because of the interest in lithium manganese oxides, several approaches have been developed for producing lithium manganese oxide powders.
In a first aspect, the invention pertains to a method of producing crystalline ternary particles comprising reacting a reactant stream comprising precursors including the three atoms of the product ternary particles, wherein the relative amounts of the three atoms in the reactant stream and the reaction conditions are selected to yield the crystalline ternary particles.
In another aspect, the invention pertains to a method of producing crystalline lithium manganese oxide particles comprising reacting a reactant stream comprising a manganese precursor and a lithium precursor, wherein the reaction is driven by energy from electromagnetic radiation.
In a further aspect, the invention pertains to a collection of particles comprising a crystalline multiple metal oxide having an average particle diameter less than about 500 nm.